PEG-urate oxidase conjugates and use thereof

Abstract

A naturally occurring or recombinant urate oxidase (uricase) covalently coupled to poly(ethylene glycol) or poly(ethylene oxide) (both referred to as PEG), wherein an average of 2 to 10 strands of PEG are conjugated to each uricase subunit and the PEG has an average molecular weight between about 5 kDa and 100 kDa. The resulting PEG-uricase conjugates are substantially non-immunogenic and retain at least 75% of the uricolytic activity of the unmodified enzyme.

1. An isolated recombinant tetrameric mammalian uricase, wherein said uricase is in a substantially tetrameric form, wherein less than 10% of said uricase is in a non-tetrameric aggregated form, and wherein said uricase is chimeric. 
     
     
       2. The isolated tetrameric uricase of  claim 1 , wherein said chimeric uricase contains portions of porcine liver and baboon liver uricases. 
     
     
       3. The isolated tetrameric uricase of  claim 2 , wherein said chimeric uricase is pig-baboon chimeric uricease. 
     
     
       4. An isolated recombinant tetrameric mammalian uricase, wherein said uricase is recombinant porcine uricase containing lysine in place of arginine at residue number 291 in SEQ ID NO:1 and serine in place of threonine at residue number 301 in SEQ ID NO:1. 
     
     
       5. An isolated recombinant tetrameric mammalian uricase, wherein said uricase has the sequence of baboon liver uricase in which tyrosine 97 in SEQ ID NO:2 has been replaced by histidine. 
     
     
       6. The isolated tetrameric uricase of  claim 1 , wherein said uricase comprises an amino terminus and a carboxyl terminus, and wherein the uricase is truncated at one terminus or both termini. 
     
     
       7. The isolated tetrameric uricase of  claim 4 , wherein said uricase comprises an amino terminus and a carboxyl terminus, and wherein the uricase is truncated at one terminus or both termini. 
     
     
       8. The isolated tetrameric uricase of  claim 5  wherein said uricase comprises an amino terminus and a carboxyl terminus, and wherein the uricase is truncated at one terminus or both termini.